Ice making machine, evaporator assembly for an ice making machine, and method of manufacturing same

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority is hereby claimed to U.S. Provisional Patent Application Ser. No. 60/693,123 filed on Jun. 22, 2005, U.S. Provisional Patent Application Ser. No. 60/709,325 filed on Aug. 18, 2005, U.S. Provisional Patent Application Ser. No. 60/753,429 filed on Dec. 23, 2005, and U.S. Provisional Patent Application Ser. No. 60/789,099, filed on Apr. 4, 2006, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Ice making machines are in widespread use for supplying cube ice in commercial operations. Typically, ice making machines produce a large quantity of clear ice by flowing water a chilled surface. The chilled surface is thermally coupled to evaporator coils that are, in turn, coupled to a refrigeration system. The chilled surface commonly contains a large number of indentations on its surface where water flowing over the surface can collect. As water flows over the indentations, it freezes into cube ice.

To harvest the ice, the evaporator coils are heated by hot, compressed refrigerant flowing through the evaporator coils, by heating elements located proximate the ice, and/or in other manners. Heat can be transferred to the chilled surface until it is warmed to a temperature sufficient to harvest the ice from the surface. Once freed from the surface, the ice cubes fall into an ice storage bin. The ice cubes produced by a typical ice making machine are pre-formed or regular in shape, and in some embodiments have a generally thin profile. In some ice making machines, the cubes are released from the chilled surface as individual cubes, while in other ice machines, the cubes are connected by a thin bridge of ice that is commonly fractured upon the ice falling into the storage bin.

Evaporators are commonly made using copper tubing in thermal contact with the chilled surface. Low-pressure, expanded refrigerant is passed through the copper tubing to chill the evaporator. The copper tubing can be secured (e.g. typically soldered or brazed) to a copper plate that distributes the chilling effect from the copper tubing. Because the copper tubing is cylindrical in shape, and because the copper plate is typically substantially flat, there is line contact between the two parts, which can reduce the efficiency and speed of heat transfer between the two parts.

SUMMARY OF THE INVENTION

In some embodiments, an ice making machine evaporator for forming ice is provided, and comprises a microchannel tube having internal walls defining a plurality of flow paths through the microchannel tube; a sheet having a first surface over which water flows during an ice making operation, the sheet coupled to the microchannel tube for thermal conductance therewith; and at least one of adhesive and cohesive bonding material coupling the first surface and the microchannel tube.

Some embodiments of the present invention provide a method of manufacturing an evaporator assembly for an ice making machine, wherein the method comprises positioning a microchannel tube having a plurality of refrigerant flow paths adjacent a surface of a sheet of thermally conductive material; pressing the microchannel tube and the sheet of thermally conductive material together; and coupling the microchannel tube and the sheet of thermally conductive material with at least one of adhesive and cohesive bonding material.

In some embodiments, an evaporator assembly for an ice making machine is provided, and comprises an ice forming sheet defining a plurality of ice forming locations, each of the plurality of ice forming locations having a width; a plurality of microchannel evaporator tubes, each of the plurality of microchannel evaporator tubes having a plurality of internal refrigerant passages and having a width substantially equal to the width of each of the plurality of ice forming locations; first insulating regions defined between adjacent ones of the plurality of microchannel evaporator tubes; and second insulating regions defined between adjacent ice forming locations along each one of the plurality of microchannel evaporator tubes.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

<figref idrefs="DRAWINGS">FIG. 1</figref> is a schematic of an ice making machine according to an embodiment of the present invention, including a microchannel evaporator assembly and other components of a refrigeration system.

<figref idrefs="DRAWINGS">FIG. 2</figref> is a partial cutaway perspective view of the evaporator assembly of <figref idrefs="DRAWINGS">FIG. 1</figref>.

<figref idrefs="DRAWINGS">FIG. 3</figref> is a cross-section of the evaporator assembly of <figref idrefs="DRAWINGS">FIG. 2</figref> taken along line <b>3</b>-<b>3</b>.

<figref idrefs="DRAWINGS">FIG. 4</figref> is a cross-section of the evaporator assembly of <figref idrefs="DRAWINGS">FIG. 2</figref> taken along line <b>4</b>-<b>4</b>.

<figref idrefs="DRAWINGS">FIG. 5</figref> is a schematic of an ice making machine according to an alternative embodiment of the present invention, including a microchannel evaporator assembly and other components of a refrigeration system.

<figref idrefs="DRAWINGS">FIG. 6</figref> is a partial cutaway perspective view of the evaporator assembly of <figref idrefs="DRAWINGS">FIG. 5</figref>.

<figref idrefs="DRAWINGS">FIG. 7</figref> is an exploded perspective view of the evaporator assembly of <figref idrefs="DRAWINGS">FIG. 5</figref>.

<figref idrefs="DRAWINGS">FIG. 8</figref> is a schematic of an ice making machine according to an alternative embodiment of the present invention, including a microchannel evaporator assembly and other components of a refrigeration system.

<figref idrefs="DRAWINGS">FIG. 9</figref> is a partial cutaway perspective view of the evaporator assembly of <figref idrefs="DRAWINGS">FIG. 8</figref>.

<figref idrefs="DRAWINGS">FIG. 10</figref> is an exploded perspective view of the evaporator assembly of <figref idrefs="DRAWINGS">FIG. 8</figref>.

<figref idrefs="DRAWINGS">FIG. 11</figref> is a partial cutaway perspective view of a microchannel evaporator assembly according to another alternative embodiment of the present invention.

<figref idrefs="DRAWINGS">FIG. 12</figref> is a partial cutaway perspective view of a microchannel evaporator assembly according to yet another alternative embodiment of the present invention.

<figref idrefs="DRAWINGS">FIG. 13</figref> is a perspective view of an evaporator according to another embodiment of the present invention.

<figref idrefs="DRAWINGS">FIG. 14</figref> is an exploded perspective view of the evaporator illustrated in <figref idrefs="DRAWINGS">FIG. 13</figref>.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

DETAILED DESCRIPTION

With reference to <figref idrefs="DRAWINGS">FIG. 1</figref>, the illustrated ice making machine <b>10</b> includes a refrigeration system having a compressor <b>14</b>, a condenser <b>18</b>, and a microchannel evaporator assembly <b>22</b>. The refrigeration system further includes a solenoid valve <b>26</b>, a dryer <b>30</b>, a heat exchanger <b>34</b>, an expansion valve <b>38</b>, and a temperature-sensing bulb <b>42</b>. Feedback control is used to modulate the expansion valve <b>38</b> in response to information from the bulb <b>42</b>. Water is provided to the evaporator assembly <b>22</b> via a water supply system including water supply ports.

With reference to <figref idrefs="DRAWINGS">FIGS. 2 and 3</figref>, the evaporator assembly <b>22</b> includes an inlet header <b>50</b>, an outlet header <b>54</b>, and a plurality of microchannel tubes <b>58</b> fluidly communicating the inlet header <b>50</b> and the outlet header <b>54</b>. The tubes <b>58</b> are substantially flat, and have a plurality of microchannels <b>62</b> formed therein (see <figref idrefs="DRAWINGS">FIG. 3</figref>). In the illustrated construction, the microchannels <b>62</b> have substantially rectangular cross-sectional shapes, with each microchannel <b>62</b> having a width dimension of about 1.4 mm and a height dimension of about 1.0 mm. Alternatively, the microchannels <b>62</b> may have different cross-sectional shapes (e.g., circular, triangular, ovular, trapezoidal, etc.), and may have a width dimension greater or less than 1 mm and a height dimension greater or less than 0.5 mm. The tubes <b>58</b> may be made from a metal having a high thermal conductivity, such as aluminum. However, the tubes <b>58</b> may be made from other metals having a relatively high thermal conductivity, such as copper or steel.

As shown in <figref idrefs="DRAWINGS">FIGS. 2 and 4</figref>, the tubes <b>58</b> are formed or bent to include recessed portions <b>68</b> extending along the width of the tubes <b>58</b>. The recessed portions are spaced from each other by a distance that approximates the length of the cubes to be produced, which is about 20 mm in the illustrated embodiment.

The evaporator assembly <b>22</b> also includes insulating members <b>66</b> positioned in and secured to the recessed portions <b>68</b> of the tubes <b>58</b>. In the illustrated construction, the insulating members <b>66</b> are configured as substantially cylindrical rods. Alternatively, the insulating members <b>66</b> may be configured to have any of a number of different shapes. For example, the insulating members <b>66</b> could have a shape that matches the shape of the recessed portions. The insulating members <b>66</b> are preferably made from a material having a relatively low thermal conductivity, such as any of a number of different plastics including PVC, polypropylene, or polyethylene.

The recessed portions <b>68</b> are sized and configured to receive the insulating members <b>66</b>, such that no portion of the insulating members <b>66</b> extends above the top surfaces of the respective tubes <b>58</b> (see <figref idrefs="DRAWINGS">FIG. 4</figref>). In the illustrated construction, the insulating members <b>66</b> are coupled to the tubes <b>58</b> by an adhesive or cohesive material <b>74</b>, such as glue, epoxy, or other adhesive, which fills the void between the insulating members <b>66</b> and top surfaces of the tubes <b>58</b>. The adhesive or cohesive material <b>74</b> preferably also has a relatively low thermal conductivity.

With reference to <figref idrefs="DRAWINGS">FIGS. 2 and 3</figref>, the evaporator assembly <b>22</b> further includes a base <b>78</b> having upstanding projections <b>82</b><i>a</i>, <b>82</b><i>b </i>configured to support the microchannels <b>58</b>. Particularly, pairs of upstanding projections <b>82</b><i>a</i>, <b>82</b><i>b </i>are configured to support side edges of adjacent tubes <b>58</b>. As shown in <figref idrefs="DRAWINGS">FIG. 3</figref>, the pairs of upstanding projections <b>82</b><i>a</i>, <b>82</b><i>b </i>include upper surfaces <b>86</b><i>a</i>, <b>86</b><i>b </i>for supporting the tubes <b>58</b>. As shown in <figref idrefs="DRAWINGS">FIGS. 2 and 4</figref>, the base <b>78</b> also includes notches <b>90</b> formed between the projections <b>82</b><i>a</i>, <b>82</b><i>b </i>along the length of the base <b>78</b>. The notches <b>90</b> in the base <b>78</b> are sized to receive the recessed portions <b>68</b> of the tubes <b>58</b>.

The evaporator assembly <b>22</b> also includes rails <b>94</b> configured to engage the pairs of upstanding projections <b>82</b><i>a</i>, <b>82</b><i>b</i>, such that the tubes <b>58</b> are secured between the rails <b>94</b> and the pairs of upstanding projections <b>82</b><i>a</i>, <b>82</b><i>b</i>. In the illustrated construction (see <figref idrefs="DRAWINGS">FIG. 3</figref>), the pairs of upstanding projections <b>82</b><i>a</i>, <b>82</b><i>b </i>each define a slot <b>102</b>, and the rails <b>94</b> each include at least one engagement portion or rib <b>98</b> configured to engage the upstanding projections <b>82</b><i>a</i>, <b>82</b><i>b</i>. In the illustrated construction, the projections <b>82</b><i>a</i>, <b>82</b><i>b </i>and the rib <b>98</b> include projecting edges <b>106</b>, <b>110</b> that engage each other. Alternatively, the projections <b>82</b><i>a</i>, <b>82</b><i>b </i>and the rails <b>94</b> may incorporate different structure to allow the rails <b>94</b> to engage the projections <b>82</b><i>a</i>, <b>82</b><i>b. </i>

Upon coupling the rails <b>94</b> to the projections <b>82</b><i>a</i>, <b>82</b><i>b</i>, the tubes <b>58</b> are sandwiched or secured between side edges of the rails <b>94</b> and the pairs of upstanding projections <b>82</b><i>a</i>, <b>82</b><i>b</i>. Such a connection is sufficient to secure the microchannels <b>58</b> to the base <b>78</b>.

With reference to <figref idrefs="DRAWINGS">FIGS. 2 and 3</figref>, the evaporator assembly <b>22</b> also includes a metal skin or sheet <b>114</b> overlying the tubes <b>58</b> and the rails <b>94</b>. Although only a portion of the sheet <b>114</b> is shown in <figref idrefs="DRAWINGS">FIGS. 2 and 3</figref>, the sheet <b>114</b> may overly the upper surface of the evaporator assembly <b>22</b>. In the illustrated construction, the sheet <b>114</b> is in direct contact with portions of the tubes <b>58</b> to facilitate conduction heat transfer between the sheet <b>114</b> and the tubes <b>58</b> in locations where an ice cube is to be formed. Alternately, adhesive and/or cohesive bonding material may be between the sheet <b>114</b> and the tubes <b>58</b> and allow conduction heat transfer therethrough. Portions of the sheet <b>114</b> not in direct contact with the tubes <b>58</b> (i.e., at the recessed portions <b>68</b>) facilitate a reduction in heat transfer between the sheet <b>114</b> and the tubes <b>58</b> in locations corresponding with the insulating members <b>66</b> in direct contact with the sheet <b>114</b>. In the illustrated embodiment, the sheet <b>114</b> is made from stainless steel, but could instead be made of other materials (such as plastic), or combinations of materials (e.g. laminated or arranged in any other manner).

The sheet <b>114</b> can have a thickness which is no greater than about 0.010 inches in some embodiments. In some embodiments, the thickness of the sheet <b>114</b> is no less than about 0.003 inches and/or is no greater than about 0.005 inches. The sheet <b>114</b> is constructed in some embodiments to be attached to the microchannel tubes <b>58</b> by a non-heated process (i.e., not at or near the melting temperature of the sheet <b>114</b>) by the use of adhesive or cohesive bonding material as described above and in greater detail below with regard to the embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref>. This bonding process can also be provided without any melting activity of the adhesive or cohesive bonding material (a process typical for welding or brazing operations), thereby significantly simplifying the assembly process.

With reference to <figref idrefs="DRAWINGS">FIG. 1</figref>, during operation of the ice-making machine <b>10</b> and the refrigeration system in a “cooling cycle,” in which ice cubes are produced, the compressor <b>14</b> receives low-pressure, substantially gaseous refrigerant from the evaporator assembly <b>22</b>, pressurizes the refrigerant, and discharges high-pressure, substantially gaseous refrigerant to the condenser <b>18</b>. Provided the solenoid valve <b>26</b> is closed, the high-pressure, substantially gaseous refrigerant is routed through the condenser <b>18</b>. In the condenser <b>18</b>, heat is removed from the refrigerant, causing the substantially gaseous refrigerant to condense into a substantially liquid refrigerant.

After exiting the condenser <b>18</b>, the high-pressure, substantially liquid refrigerant is dried by the dryer <b>30</b> and is routed through the heat exchanger <b>34</b>. While passing through the heat exchanger <b>34</b>, the high-pressure, substantially liquid refrigerant absorbs heat from the low-pressure, substantially gaseous refrigerant passing through the heat exchanger <b>34</b> en route to the inlet of the compressor <b>14</b>. After exiting the heat exchanger <b>34</b>, the high-pressure liquid refrigerant encounters the expansion valve <b>38</b>, which reduces the pressure of the substantially liquid refrigerant for introduction into the evaporator assembly <b>22</b>. Specifically, low-pressure, liquid refrigerant enters the inlet header <b>50</b> and the tubes <b>58</b>. The refrigerant absorbs heat from the tubes <b>58</b> and vaporizes as the refrigerant passes through the tubes <b>58</b>. Low-pressure, substantially gaseous refrigerant is discharged from the outlet header <b>54</b> for re-introduction into the inlet of the compressor <b>14</b>.

As shown in <figref idrefs="DRAWINGS">FIG. 1</figref>, the evaporator assembly <b>22</b> includes baffles <b>120</b> that configure the assembly as a multi-pass evaporator. In this design, refrigerant is routed back and forth between the inlet header <b>50</b> and outlet header <b>54</b>. In the illustrated construction, the evaporator assembly <b>22</b> is configured as a 3-pass evaporator. Alternatively, the evaporator assembly <b>22</b> may include more or less than three passes.

With reference to <figref idrefs="DRAWINGS">FIG. 2</figref>, the sheet <b>114</b> and rails <b>94</b> define a plurality of fluid flow channels <b>118</b> on the evaporator assembly <b>22</b>. The insulating members <b>66</b> and the rails <b>94</b> divide the fluid flow channels <b>118</b> into insulated regions <b>122</b><i>a</i>, <b>122</b><i>b </i>and non-insulated regions <b>126</b> (see <figref idrefs="DRAWINGS">FIGS. 3 and 4</figref>). As used herein, “insulated region” and “non-insulated region over which water flows during an ice making operation the sheet coupled to the microchannel tube for thermal conductance therewith wherein the ice forming sheet has a thickness no greater than about 0.010 inches. are relative terms used to indicate that one region (i.e., the non-insulated region) is colder during the cooling cycle so that ice will more readily form in that region compared to the insulated region. These terms should not be interpreted to mean that one region must be insulated and the other uninsulated, or that one region must include a dedicated insulation material. The non-insulated regions <b>126</b> are regions on the sheet <b>114</b> that are arranged for sufficient thermal conduction with the tubes <b>58</b> to form ice on the sheet <b>114</b>, whereas the insulated regions <b>122</b><i>a</i>, <b>122</b><i>b </i>are regions on the sheet <b>114</b> that are sufficiently thermally insulated from the tubes <b>58</b> so that ice will not form in the insulated regions <b>122</b><i>a</i>, <b>122</b><i>b</i>. In this regard, the insulated regions can be insulated by insulation material, air, an adequate combination of thermal resistance and distance, and the like.

It should be understood that the insulated regions <b>122</b><i>a</i>, <b>122</b><i>b </i>and non-insulated regions <b>126</b> can be created in a number of different ways. For example, the tubes <b>58</b> can have a thinner wall thickness in the non-insulated regions <b>126</b> compared to the insulated regions <b>122</b><i>a</i>, <b>122</b><i>b </i>in order to increase the rate at which ice is formed in the non-insulated regions <b>126</b>. If the wall thickness in the insulated regions <b>122</b><i>a</i>, <b>122</b><i>b </i>is thick enough, there may be little or no need for the recessed portions <b>68</b> and insulating members <b>66</b>. Alternatively, the materials used in the two regions can have different heat transfer coefficients, thus resulting in different abilities to cool the surface upon which water flows.

During operation of the illustrated ice-making machine <b>10</b> in the cooling cycle, water is routed through each of the fluid flow channels <b>118</b> along outward surfaces thereof. Water freezes on portions of the sheet <b>114</b> corresponding with portions of the tubes <b>58</b> which are in direct contact with the sheet <b>114</b> (i.e., the “non-insulated regions <b>126</b>”). The insulating members <b>66</b> inhibit the freezing of water on portions of the sheet <b>114</b> spaced along the fluid flow channels <b>118</b> (i.e., the “insulated regions <b>122</b><i>a</i>”), such that separate and distinct ice cubes form in the fluid flow channels <b>118</b>. The spaces between adjacent tubes <b>58</b> and the rails <b>94</b> occupying those spaces inhibit the freezing of water on portions of the sheet <b>114</b> between adjacent tubes <b>58</b> (i.e., the “insulated regions <b>122</b><i>b</i>”).

To harvest the blocks of ice or the ice cubes, the cooling cycle is stopped and water is stopped from flowing through the fluid flow channels <b>118</b>. The solenoid valve <b>26</b> is then opened to allow high-pressure, substantially hot gaseous refrigerant discharged from the compressor <b>14</b> to enter the evaporator assembly <b>22</b>. The high-pressure, substantially hot gaseous refrigerant “defrosts” the tubes <b>58</b> in the evaporator assembly <b>22</b> to facilitate the release of ice from the sheet <b>114</b>. The individual ice cubes will eventually slide down the fluid flow channels <b>118</b> and fall onto an ice rack (not shown) in a storage bin (not shown). At this time, the harvest cycle is stopped, and the cooling cycle is restarted to create more ice cubes.

<figref idrefs="DRAWINGS">FIGS. 5-7</figref> illustrate another ice making machine <b>210</b> according to an embodiment of the present invention. The elements and features of this embodiment are similar in many ways to elements and features in the embodiments described above and illustrated in <figref idrefs="DRAWINGS">FIGS. 1-4</figref>. Accordingly, the following description focuses primarily upon those elements and features that are different from the embodiments described above. Reference should be made to the above description for additional information regarding the elements, features, and possible alternatives to the elements and features of the ice making machine <b>210</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 5-7</figref> and described below.

With reference to <figref idrefs="DRAWINGS">FIG. 5</figref>, the illustrated ice making machine <b>210</b> includes a refrigeration system having a compressor <b>214</b>, a condenser <b>218</b>, and a microchannel evaporator assembly <b>222</b>. The refrigeration system further includes a solenoid valve <b>226</b>, a dryer <b>230</b>, a heat exchanger <b>234</b>, an expansion valve <b>238</b>, and a temperature-sensing bulb <b>242</b>. Feedback control is used to modulate the expansion valve <b>238</b> in response to information from the bulb <b>242</b>. Water is provided to the evaporator assembly <b>222</b> via a water supply system including water supply ports.

With reference to <figref idrefs="DRAWINGS">FIGS. 6 and 7</figref>, the evaporator assembly <b>222</b> of the illustrated embodiment includes an inlet header <b>250</b>, an outlet header <b>254</b>, and a plurality of microchannel tubes <b>258</b> fluidly communicating the inlet header <b>250</b> and the outlet header <b>254</b>. The cross-sectional shape of the tubes <b>258</b> is substantially identical to that of the tubes <b>58</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 2 and 3</figref>, and can take any of the other forms described above with reference to the embodiment of <figref idrefs="DRAWINGS">FIGS. 1-4</figref>.

In operation of the illustrated evaporator assembly <b>222</b>, low-pressure, substantially liquid refrigerant enters the inlet header <b>250</b> proximate the top of <figref idrefs="DRAWINGS">FIG. 6</figref>, passes through the microchannel tubes <b>258</b> as shown by the arrows in phantom in <figref idrefs="DRAWINGS">FIG. 6</figref>, and exits the evaporator assembly <b>222</b> as substantially gaseous refrigerant via the outlet header <b>254</b> proximate the bottom of <figref idrefs="DRAWINGS">FIG. 6</figref>. Flow of refrigerant through the inlet header <b>250</b>, microchannel tubes <b>258</b>, and outlet header <b>254</b> is determined by baffles <b>320</b> in the inlet and outlet headers <b>250</b>, <b>254</b> (see <figref idrefs="DRAWINGS">FIGS. 5 and 6</figref>).

The evaporator assembly <b>222</b> further includes a frame <b>228</b> adapted to support the microchannel tubes <b>258</b> and to hold the microchannel tubes <b>258</b> in position with respect to one another. The frame <b>228</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 6 and 7</figref> sandwiches or supports the microchannel tubes <b>258</b> between first and second sides of the evaporator assembly <b>222</b>, and holds the microchannel tubes <b>258</b> in a substantially parallel and spaced configuration (described in greater detail below).

The frame <b>228</b> in the illustrated embodiment includes a number of rails <b>294</b> running across the evaporator assembly <b>222</b> and crossing the microchannel tubes <b>258</b>. The rails <b>294</b> extend in a substantially perpendicular manner with respect to the microchannel tubes <b>258</b>, and frame the sides of a series of fluid flow channels <b>318</b> in which ice is produced by the evaporator assembly <b>222</b>. The rails <b>294</b> in the illustrated embodiment extend away from the microchannel tubes <b>258</b> on both sides of the evaporator assembly <b>222</b>, thereby defining a framework of fluid flow channels <b>318</b> on both sides of the evaporator assembly <b>222</b>. The frame <b>228</b> further includes water entrance and exit pieces <b>319</b>, <b>321</b> at opposite ends of the frame <b>228</b>, both of which have surfaces across which water flows on the way into and out of the fluid flow channels <b>318</b>, respectively.

The fluid flow channels <b>318</b> can be lined with a thermally conductive material, including any of the materials described above with reference to the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 1-4</figref>. For example, the fluid flow channels <b>318</b> in the evaporator assembly <b>222</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 5-7</figref> are lined with a sheet <b>314</b>, such as stainless steel sheet, a foil of other metallic material, or a non-metallic thermally conductive sheet. The sheet <b>314</b> in the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 5-7</figref> covers the rails <b>294</b> and the faces of the microchannel tubes <b>258</b>, thereby defining the fluid flow channels <b>318</b> described above. Each fluid flow channel <b>318</b> can therefore have a generally U-shaped cross-section. Adhesive or cohesive bonding material can be used to attach the sheet <b>314</b> to the microchannel tubes <b>258</b>. Bonding materials and uses thereof for this and other embodiments of the present invention described and illustrated herein are discussed in further detail below.

The sheet <b>314</b> can have a thickness which is no greater than about 0.010 inches in some embodiments. In some embodiments, the thickness of the sheet <b>314</b> is no less than about 0.003 inches and/or is no greater than about 0.005 inches. The sheet <b>314</b> is constructed in some embodiments to be attached to the microchannel tubes <b>258</b> by a non-heated process (i.e., not at or near the melting temperature of the sheet <b>314</b>) by the use of adhesive or cohesive bonding material as described above and in greater detail below with regard to the embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref>. This bonding process can also be provided without any melting activity of the adhesive or cohesive bonding material (a process typical for welding or brazing operations), thereby significantly simplifying the assembly process.

The bottoms of the fluid channels <b>318</b> on both sides of the evaporator assembly <b>222</b> are in contact with the microchannel tubes <b>258</b> in a number of locations. At these locations, the sheet <b>314</b> lining the fluid flow channels <b>318</b> is in thermal conduction communication with the microchannel tubes <b>258</b>. Therefore, these locations define non-insulated regions <b>326</b> of the fluid flow channels <b>318</b>. Ice cubes can be formed in these non-insulated regions <b>326</b> during operation of the evaporator assembly <b>222</b>.

The fluid flow channels <b>318</b> of the evaporator assembly <b>222</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 5-7</figref> also have a number of insulated regions <b>322</b> for purposes of producing ice in selected areas of the fluid flow channels <b>318</b>. Although insulated regions <b>322</b> can be created in any of the manners described above (e.g., by insulating elements located adjacent the microchannel tubes <b>258</b>, and the like), insulated regions <b>322</b> are defined in the evaporator assembly <b>222</b> by spaces <b>224</b> between adjacent microchannel tubes <b>258</b>. These spaces <b>224</b> can be left empty, or can be partially or entirely occupied by other insulating structure(s) of the evaporator assembly <b>222</b>. In either case, the spaces <b>224</b> between adjacent tubes <b>258</b> inhibit the conduction of heat from areas of the fluid flow channels <b>318</b> adjacent the spaces <b>224</b> to the microchannel tubes <b>258</b>. The rails <b>294</b> can constitute additional insulated regions along the length of each microchannel tube <b>258</b> as they divide the length of each microchannel tube <b>258</b> into a number of ice forming locations or non-insulated regions <b>326</b>.

The spaces <b>224</b> between adjacent microchannel tubes <b>258</b> can be defined in a number of different ways in an evaporator assembly <b>222</b>. By way of example only, the microchannel tubes <b>258</b> in the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 5-7</figref> are arranged in a substantially parallel and spaced arrangement to create the spaces <b>224</b>. As described above, the microchannel tubes <b>258</b> in the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 5-7</figref> are arranged in a direction perpendicular to the fluid flow channels <b>318</b>, thereby defining the non-insulated regions <b>326</b> of the fluid flow channels <b>318</b>.

With reference again to the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 5-7</figref>, during operation of the ice-making machine <b>210</b> in the cooling cycle, water is routed through each of the fluid flow channels <b>318</b>. Water freezes at locations in the fluid flow channels <b>318</b> corresponding with portions of the microchannel tubes <b>258</b> in contact with the sheet <b>314</b> lining the fluid flow channels <b>318</b> (i.e., the “non-insulated regions <b>326</b>”). The spaces between adjacent microchannel tubes <b>258</b> inhibits the freezing of water in portions of the fluid flow channels <b>318</b> (i.e., the insulated regions <b>322</b><i>b</i>), such that separate and distinct ice cubes form in the fluid flow channels <b>318</b>. The rails <b>294</b> across each microchannel tube <b>258</b> divide adjacent fluid flow channels <b>318</b> (i.e., with the “insulated regions <b>322</b><i>a</i>”) and their respective ice forming locations (i.e., the “non-insulated regions <b>326</b>”). Ice can be harvested in a manner similar to that of the first embodiment illustrated in <figref idrefs="DRAWINGS">FIGS. 1-4</figref>.

In the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 5-7</figref>, fluid flow channels <b>318</b> are located on both sides of the evaporator assembly <b>222</b>. In other embodiments, fluid flow channels <b>318</b> are located on only one side of the evaporator assembly <b>222</b>.

The evaporator assembly <b>222</b> can have any orientation desired, depending at least partially upon the position and orientation of the fluid flow channels <b>318</b> described above and upon the flow path of water through the evaporator assembly <b>222</b>. For example, an evaporator assembly <b>222</b> having fluid flow channels <b>318</b> on both sides of the evaporator assembly <b>222</b> (see <figref idrefs="DRAWINGS">FIGS. 6 and 7</figref>) can be oriented substantially vertically or at a relatively steep angle, whereas an evaporator assembly <b>222</b> having fluid flow channels <b>318</b> on only one side of the evaporator assembly <b>222</b> can be oriented at a relatively small angle with respect to a horizontal plane.

<figref idrefs="DRAWINGS">FIGS. 8-10</figref> illustrate an ice making machine <b>410</b> according to another embodiment of the present invention. The elements and features of this embodiment are similar in many ways to elements and features in the embodiments described above in connection with <figref idrefs="DRAWINGS">FIGS. 1-7</figref>. Accordingly, the following description focuses primarily upon those elements and features that are different from the embodiments described above (except where otherwise noted). Reference should be made to the above description for additional information regarding the elements, features, and possible alternatives to the elements and features of the ice making machine <b>410</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 8-10</figref> and described below.

With reference to <figref idrefs="DRAWINGS">FIG. 8</figref>, the illustrated ice making machine <b>410</b> includes a refrigeration system having a compressor <b>414</b>, a condenser <b>418</b>, and a microchannel evaporator assembly <b>422</b>. The refrigeration system further includes a solenoid valve <b>426</b>, a dryer <b>430</b>, a heat exchanger <b>434</b>, an expansion valve <b>438</b>, and a temperature-sensing bulb <b>442</b>. Feedback control is used to modulate the expansion valve <b>438</b> in response to information from the bulb <b>442</b>. Water is provided to the evaporator assembly <b>422</b> via a water supply system including water supply ports. With the exception of the evaporator assembly (described in greater detail below), the refrigeration system is substantially unchanged from that of the previously described embodiments.

With additional reference to <figref idrefs="DRAWINGS">FIGS. 9 and 10</figref>, the illustrated evaporator assembly <b>422</b> includes an inlet header <b>450</b>, an outlet header <b>454</b>, and a plurality of microchannel tubes <b>458</b> therebetween. The evaporator assembly <b>422</b> provides an example of a different type of refrigerant flow path through the inlet header <b>450</b>, outlet header <b>454</b>, and microchannel tubes <b>458</b>, wherein the serpentine path of refrigerant through the evaporator assembly <b>422</b> is a single path rather than a dual parallel serpentine path as illustrated in the earlier embodiments. Accordingly, the inlet and outlet headers <b>450</b>, <b>454</b> in the embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref> are provided with additional baffles <b>520</b> to result in the single serpentine path shown. Still other types of refrigerant paths through the evaporator assembly <b>422</b> are possible, and fall within the spirit and scope of the present invention.

A sheet <b>514</b> of material having recesses <b>518</b> is positioned on each side of the microchannel tubes <b>458</b>, thereby enabling the production of ice on both sides of the evaporator assembly <b>422</b> as will be described in greater detail below. In other embodiments, only one side of the evaporator assembly <b>422</b> is provided with a sheet upon which ice is formed. Each sheet <b>514</b> can be formed from a single sheet of material, such that recesses <b>518</b> can be completely defined by the sheet <b>514</b> (e.g., such as by die, press, cast, mold, etc.). In some embodiments, a number of such recesses <b>518</b> can be defined in and by the same sheet. For example, in some embodiments, all of the recesses <b>518</b> on a side of the evaporator <b>518</b> are defined by the same sheet <b>514</b>. Each recess can be completely defined by the same sheet <b>514</b>. In this manner, the ice-forming surfaces for each individual cube need not necessarily be constructed of multiple pieces assembled together as is common in the art.

Between each sheet <b>514</b> and the microchannel tubes <b>458</b> is a bonding material <b>437</b>. The bonding material <b>437</b> is positioned to bond each sheet <b>514</b> to the microchannel tubes <b>458</b>. In some embodiments (e.g., in some cases where the bonding material <b>437</b> is applied only to the microchannel tubes <b>458</b> during assembly), the bonding material <b>437</b> only contacts the bottom of each recess <b>518</b>. In other embodiments (e.g., in some cases where the bonding material <b>437</b> is applied only to the underside of the sheet <b>514</b> during assembly), the bonding material <b>437</b> can contact the bottom of each recess <b>518</b> and areas surrounding each recess <b>518</b>. The bonding material <b>437</b> couples the bottoms of the recesses <b>518</b> to the microchannel tubes <b>458</b>. By virtue of the flat shape of the microchannel tubes <b>458</b> and the non-planar shape of each sheet <b>514</b>, a number of insulated regions <b>522</b><i>a </i>are defined between the sheets <b>514</b> and the microchannel tubes <b>458</b>. Additional insulated regions <b>522</b><i>b </i>are defined between adjacent microchannel tubes <b>458</b>. Either or both types of insulated regions can be empty or can be partially or entirely filled with any thermally insulative material desired to prevent the formation of ice between the recesses <b>518</b>. Likewise, the bottoms of the recesses <b>518</b> are in thermal conduction communication with the microchannel tubes <b>458</b>, and thereby define locations upon which ice forms during operation of the refrigeration system as described with reference to previous embodiments of the invention.

The bonding material <b>437</b> used to connect the sheets <b>514</b> to the microchannel tubes <b>458</b> can include epoxy, glue, tape, or other adhesive or cohesive bonding material. In some embodiments, the bonding material <b>437</b> is double-sided tape. The bonding material <b>437</b> can be thermally conductive or relatively non-thermally conductive. In some embodiments, the bonding material <b>437</b> includes a foam adhesive or cohesive bonding material. In such embodiments, the bonding material can be a closed cell foam. Also, the bonding material <b>437</b> can comprise a visco-elastic foam, and can be substantially moisture-resistant or water-impermeable. Moisture-resistant or water-impermeable tape can be used to prevent water from entering spaces between the sheet(s) <b>514</b> and the microchannel tubes <b>458</b>, which in some cases can shorten the life of the evaporator assembly <b>422</b> and/or reduce its efficiency. The bonding material <b>437</b> in the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref> is 3-M™ VHB™ visco-elastic acrylic foam double-sided tape, is moisture resistant, and can be obtained in varieties suitable for low temperature applications, such as temperatures at or below 0 degrees Celsius. Adhesive and/or cohesive bonding material can be provided according to the description given above in other structural embodiments of the invention.

With continued reference to the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref>, the sheet <b>514</b> comprises a thin layer of thermally conductive material, such as stainless steel. In other embodiments, the sheet <b>514</b> can comprise other thermally conductive materials. In some embodiments, the sheet <b>514</b> can have a thickness no greater than about 0.010 inches. In some embodiments, the sheet <b>514</b> can have a thickness of no less than about 0.003 inches and no greater than about 0.005 inches. Thin sheet thickness can make welding, brazing, and other heat intensive or melting processes unacceptable for coupling sheets <b>514</b> to the microchannel tubes <b>458</b>. Thus, a bonding process which forms a bond between the microchannel tubes <b>458</b> and the sheets <b>514</b> without approaching the melting temperature of either the tubes <b>458</b> or the sheets <b>514</b> can be utilized. This bonding process can also be provided without any melting activity of the adhesive or cohesive bonding material (a process typical for welding or brazing operations), thereby significantly simplifying the assembly process. The sheet thicknesses and bonding processes described above can also be applied to any of the other embodiments of the present invention.

The recesses <b>518</b> in the illustrated embodiment have a substantially square shape with beveled edges, although in other embodiments the recesses <b>518</b> can have sides that are substantially orthogonal to the bottoms of the recesses <b>518</b>. The beveled edges of the recesses in the illustrated embodiment assist in releasing ice during the harvesting process. One of ordinary skill in the art will appreciate that many different shapes of recesses <b>518</b> can be employed, including round, oval, trapezoidal, irregular, and other shapes. The recesses <b>518</b> in the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref> are arranged in rows along the length of each microchannel tube <b>458</b>. The insulated regions <b>522</b><i>a </i>between adjacent recesses <b>518</b> in a given row prevent localized ice formation, and thereby create a division between adjacent ice cubes along each microchannel tube <b>458</b>. Between the recesses <b>518</b> of adjacent rows, insulated regions <b>522</b><i>b </i>perform a similar function. Also, spaces <b>424</b> between adjacent microchannel tubes <b>458</b> provide additional insulation at the insulated regions <b>522</b><i>b. </i>

<figref idrefs="DRAWINGS">FIG. 11</figref> illustrates a microchannel evaporator assembly <b>622</b> according to another embodiment of the present invention. The elements and features of this embodiment are similar in many ways to elements and features in the embodiments described above in connection with <figref idrefs="DRAWINGS">FIGS. 1-10</figref>. Accordingly, the following description focuses primarily upon those elements and features that are different from the embodiments described above. Reference should be made to the above description for additional information regarding the elements, features, and possible alternatives to the elements and features of the microchannel evaporator assembly <b>622</b> illustrated in <figref idrefs="DRAWINGS">FIG. 11</figref> and described below.

The evaporator assembly <b>622</b> illustrated in <figref idrefs="DRAWINGS">FIG. 11</figref> includes sheets <b>714</b> of thermally conductive material overlying a number of microchannel tubes <b>658</b>. The sheets <b>714</b> can be similar in construction to those described in detail above, but being shaped in a different form. Each sheet <b>714</b> is formed with channels <b>718</b> running along a direction substantially perpendicular to the tubes <b>658</b>. Similar to previously-described embodiments, the evaporator assembly <b>622</b> is provided with insulated regions <b>722</b><i>a</i>, <b>722</b><i>b </i>and non-insulated regions <b>726</b>. In the embodiment shown in <figref idrefs="DRAWINGS">FIG. 11</figref>, the insulated regions <b>722</b><i>a </i>run between and are parallel to adjacent channels <b>718</b>. The insulated regions <b>722</b><i>a </i>provide an insulating effect by creating a gap between each sheet <b>714</b> and the microchannel tubes <b>658</b>, significantly reducing the amount of heat transferred therebetween. In some embodiments, the insulated regions <b>722</b><i>a </i>create a gap only above the microchannel tubes <b>658</b>, such that the insulated regions <b>722</b><i>a </i>are periodically interrupted between microchannel tubes <b>658</b>. The insulated regions <b>722</b><i>b </i>are maintained, as in previous embodiments, by the spaces <b>624</b> between adjacent tubes <b>658</b>. As described in earlier embodiments, any or all of the insulated regions <b>722</b><i>a</i>, <b>722</b><i>b </i>can be partially or entirely filled with insulating material, or can instead be empty as shown in <figref idrefs="DRAWINGS">FIG. 11</figref>. A bonding material <b>637</b> (described in greater detail above with reference to the embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref>) is provided between the tubes <b>658</b> and each sheet <b>714</b> in order to couple the sheets <b>714</b> to the microchannel tubes <b>658</b>. In some embodiments, only one side of the evaporator assembly <b>622</b> is provided with a sheet <b>714</b> of thermally conductive material.

It should be noted that the sheets <b>714</b> in the illustrated embodiment of <figref idrefs="DRAWINGS">FIG. 11</figref> are sufficiently rigid to maintain the shape of each channel <b>718</b> (following repeated ice forming and harvesting cycles) without the need for a frame or base for structural integrity of the assembly. Also, the use of bonding material <b>637</b> to couple the sheets <b>714</b> to the microchannel tubes <b>658</b> provides sufficient structural strength to retain the microchannel tubes <b>658</b> in the desired spaced positions with respect to one another.

<figref idrefs="DRAWINGS">FIG. 12</figref> illustrates another microchannel evaporator assembly <b>822</b> according to yet another embodiment of the present invention. The elements and features of this embodiment are similar in many ways to elements and features in the embodiments described above in connection with <figref idrefs="DRAWINGS">FIGS. 1-11</figref>. Accordingly, the following description focuses primarily upon those elements and features that are different from the embodiments described above. Reference should be made to the above description for additional information regarding the elements, features, and possible alternatives to the elements and features of the microchannel evaporator assembly <b>822</b> illustrated in <figref idrefs="DRAWINGS">FIG. 12</figref> and described below.

The evaporator assembly <b>822</b> illustrated in <figref idrefs="DRAWINGS">FIG. 12</figref> includes sheets <b>914</b> of heat-conductive material overlying a number of microchannel tubes <b>858</b>. Both sheets <b>914</b> are substantially flat. Microchannel tubes <b>858</b> are positioned between an inlet header <b>850</b> and an outlet header <b>854</b>. As illustrated, the microchannel tubes <b>858</b> are substantially non-planar, such that each tube <b>858</b> includes alternating upper portions <b>858</b><i>a </i>and lower portions <b>858</b><i>b </i>(upper and lower being relative terms used only to describe the orientation as illustrated in <figref idrefs="DRAWINGS">FIG. 12</figref>). The sheets <b>914</b> are positioned upon opposite sides of the microchannel tubes <b>858</b>, and are coupled to the microchannel tubes <b>858</b> by a bonding material <b>837</b>. By virtue of the shapes of the microchannel tubes <b>858</b>, insulated regions <b>922</b><i>a</i>, <b>922</b><i>b </i>and non-insulated regions <b>926</b> exist at different locations along the sheet <b>914</b>. Non-insulated regions <b>926</b> exist at locations where the sheet <b>914</b> is coupled to the upper portions <b>858</b><i>a </i>of the microchannel tubes <b>858</b>, while insulated regions <b>922</b><i>a</i>, <b>922</b><i>b </i>exist at locations where the sheet <b>914</b> is not bonded to the tubes <b>858</b> (i.e., adjacent each lower portion <b>858</b><i>b</i>) and adjacent spaces <b>824</b> between adjacent tubes <b>858</b>, respectively. In some embodiments, only one side of the evaporator assembly <b>822</b> is provided with a sheet <b>914</b> of thermally conductive material.

The sheets <b>914</b> in the illustrated embodiment of <figref idrefs="DRAWINGS">FIG. 12</figref> are sufficiently rigid to maintain the flat shape of the sheets <b>914</b> without the need for a frame or base for structural integrity of the assembly. Also, the use of bonding material <b>837</b> to couple the sheets <b>914</b> to the microchannel tubes <b>858</b> provides sufficient structural strength to retain the microchannel tubes <b>858</b> in the desired spaced positions with respect to one another.

<figref idrefs="DRAWINGS">FIGS. 13 and 14</figref> illustrate a microchannel evaporator assembly <b>1022</b> according to another embodiment of the present invention. The elements and features of this embodiment are similar in many ways to elements and features in the embodiments described above in connection with <figref idrefs="DRAWINGS">FIGS. 1-12</figref>. Accordingly, the following description focuses primarily upon those elements and features that are different from the embodiments described above. Reference should be made to the above description for additional information regarding the elements, features, and possible alternatives to the elements and features of the microchannel evaporator assembly <b>1022</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13 and 14</figref> and described below.

The evaporator assembly <b>1022</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13 and 14</figref> provides an example of the manner in which microchannel tubes <b>1058</b> and sheets <b>1014</b> can be oriented and arranged differently while still falling within the spirit and scope of the present invention. For example, the evaporator assembly <b>1022</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13 and 14</figref> utilizes a number of sheets <b>1014</b> defining different portions of the evaporator assembly <b>1022</b>. Also, <figref idrefs="DRAWINGS">FIGS. 13 and 14</figref> provide an example of how an evaporator assembly <b>1022</b> can have two or more non-coplanar sheets <b>1014</b> coupled at different locations along the length of one or more microchannel tubes <b>1058</b>.

The evaporator assembly <b>1022</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13 and 14</figref> includes a housing <b>1028</b> and sheets <b>1014</b> of thermally conductive material overlying microchannel tubes <b>1058</b>. The housing <b>1028</b> of the illustrated embodiment is substantially rectangular, and includes opposing support members <b>1031</b>. The housing <b>1028</b> includes ribs <b>1032</b> extending between first and second opposing sides <b>1035</b>, <b>1036</b>. Support posts <b>1039</b> extend substantially vertically from the ribs <b>1032</b>. The support members <b>1031</b> are substantially identical and comprise a majority of the first and second sides <b>1035</b>, <b>1036</b>. The support members <b>1031</b> define a plurality of substantially vertical apertures <b>1040</b>. The housing <b>1028</b> is adapted to receive the support members <b>1031</b> such that the apertures <b>1040</b> of the support members <b>1031</b> at least partially receive the support posts <b>1039</b> of the housing <b>1028</b>. The support members <b>1031</b> also include tabs <b>1043</b> that support the support members <b>1031</b> with respect to the housing <b>1028</b>.

In other embodiments, the housing <b>1028</b> can have any other shape adapted to support the microchannel tubes <b>1058</b>. For example, the housing <b>1028</b> can be longer or wider than that shown in <figref idrefs="DRAWINGS">FIGS. 13 and 14</figref> in order to accommodate more passes of the microchannel tube <b>1058</b> or to accommodate longer passes of the microchannel tube <b>1058</b>, respectively. As another example, the housing <b>1028</b> can be thicker than that shown in <figref idrefs="DRAWINGS">FIGS. 13 and 14</figref> in order to accommodate a wider microchannel tube <b>1058</b>. In other embodiments, no housing <b>1028</b> exists, in which case the microchannel tube <b>1058</b> and the sheets <b>1014</b> can be supported with respect to a structure (e.g., within an ice making machine) in any other suitable manner.

The microchannel tubes <b>1058</b> of the embodiment illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref> are arranged in a non-planar, serpentine configuration between an inlet <b>1050</b> and an outlet <b>1054</b>. The serpentine configuration can provide a single piece of microchannel tubing <b>1058</b> for refrigerant flow through the evaporator assembly <b>1022</b>. In other embodiments, this serpentine configuration is defined by two or more pieces of microchannel tubing are <b>1058</b> connected end-to-end (i.e., in series) in any manner.

With continued reference to the embodiment illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref>, the serpentine configuration can be formed by bending the microchannel tubing <b>1058</b>. Alternatively, one or more of the bent portions of the microchannel tubing <b>1058</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref> can be replaced by another tube (e.g., a separate manifold or other connecting tube, another piece of microchannel tubing, and the like) coupled to the other illustrated portions of the microchannel tubing <b>1058</b>. If employed, inlet and outlet manifolds (or other connecting tubes) can be used as described earlier to define serpentine flow, parallel flow, or other flow paths through the tubes <b>1058</b>.

The tubes <b>1058</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref> are adapted to extend through the apertures <b>1040</b> of the support members <b>1031</b>, and to rest on the support posts <b>1039</b>. The tubes <b>1058</b> extend through the housing <b>1028</b> four times. In some embodiments, the tubes <b>1058</b> extend through a larger or smaller housing a greater or lesser number of times, depending on output capacity required of the evaporator assembly <b>1022</b>.

The sheets <b>1014</b> of thermally conductive material can include substantially flat regions <b>1118</b> configured to exchange heat with the microchannel tubes <b>1058</b> and insulated regions <b>1122</b> configured to prevent heat transfer between the sheets <b>1014</b> and the microchannel tubes <b>1058</b>. As described in earlier embodiments, any or all of the insulated regions <b>1122</b> can be partially or entirely filled with insulating material, or can be otherwise void of thermally conductive material. A bonding material <b>1037</b> (described in greater detail above in connection with the embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref>) is provided between the tubes <b>1058</b> and each sheet <b>1014</b> in order to couple the sheets <b>1014</b> to the microchannel tubes <b>1058</b>. In the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 13-14</figref>, the sheets <b>1014</b> are folded in half such that they substantially surround the microchannel tubes <b>1058</b>, and permit formation of ice on both sides of the tubes <b>1058</b>. Alternatively, sheets <b>1014</b> on opposite sides of the microchannel tube <b>1058</b> can define one or more sleeves surrounding the microchannel tube <b>1058</b>, such as by sliding a sleeve to a desired location along the microchannel tube <b>1058</b> before bending the microchannel tube <b>1058</b> as described above. In some embodiments, separate sheets <b>1014</b> can be coupled to the opposite sides of the microchannel tubes <b>1058</b>.

It should be noted that the sheets <b>1014</b> in the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 13-14</figref> are sufficiently rigid to maintain the shape of each insulated region <b>1122</b> (following repeated ice forming and harvesting cycles) without the need for a frame or base for structural integrity of the assembly. Also, the use of bonding material <b>1037</b> to couple the sheets <b>1014</b> to the microchannel tubes <b>1058</b> provides sufficient structural strength to retain the sheets <b>1014</b> with respect to the microchannel tubes <b>1058</b>. The insulated regions <b>1122</b> in the embodiment of <figref idrefs="DRAWINGS">FIGS. 13-14</figref> are defined by projections formed in the sheets <b>1014</b>. In some embodiments, the insulated regions <b>1122</b> can be any desired shape to alter the shape of the ice formed on the flat regions <b>1118</b>. In the illustrated embodiment of <figref idrefs="DRAWINGS">FIGS. 13-14</figref>, nozzles (not shown) are positioned to spray water on the sheets <b>1014</b> to form ice. In some embodiments, water can flow over the sheets <b>1014</b> to form ice as is described in earlier embodiments.

The evaporator assembly <b>1022</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref> includes one serpentine piece of microchannel tubing <b>1058</b> overlaid by sheets <b>1014</b> of material on opposite faces of the microchannel tubing <b>1058</b>. In some embodiments, two or more pieces of microchannel tubing <b>1058</b> can be positioned in a vertically-aligned and stacked configuration to increase the output capacity of the evaporator assembly <b>1022</b>. Accordingly, one or more additional serpentine-shaped microchannel tubes <b>1058</b> overlaid with sheets <b>1014</b> can be positioned above or below the microchannel tubing <b>1058</b> and sheets <b>1014</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref>, whereby water flowing over the flat regions <b>1118</b> of one sheet <b>1014</b> then flow over another flat region <b>1118</b> of an adjacent sheet <b>1014</b>, thereby providing additional ice making capacity, as desired. By utilizing two or more of such microchannel and tube assembly “layers”, different portions of the evaporator assembly <b>1022</b> can be operated independently of one another. Therefore, different potions of such an evaporator assembly <b>1022</b> can be selectively activated in order to adjust the rate of ice production of the evaporator assembly <b>1022</b>.

Each pass of the microchannel tubing <b>1058</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref> produces a single row of ice on each side of the microchannel tubing <b>1058</b>. In other embodiments, two or more parallel and spaced microchannel tubes <b>1058</b> are sandwiched between the same sheets <b>1014</b>, thereby enabling two or more rows of ice to be produced on each side of the microchannel tubing <b>1058</b>.

In the embodiment illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref>, water is sprayed onto the sheets <b>1014</b> in order to form ice thereon. In other embodiments, water can flow over the sheets <b>1014</b> from an overhead water manifold, gutter, or other water source.

The evaporator assembly <b>1022</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref> has a number of non-insulated regions <b>1118</b> on which ice form and a number of insulated regions <b>1122</b> on which ice does not form. The insulated regions <b>1122</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref> are defined by ribs as described above. However, any of the various manners described herein for defining insulated and non-insulated regions can also or instead be utilized. For example, substantially flat sheets <b>1014</b> (e.g., without ribs or other insulating features) can be coupled to non-planar microchannel tubing <b>1058</b>, such as any of the non-planar microchannel tubing <b>1058</b> disclosed above in connection with the embodiment of <figref idrefs="DRAWINGS">FIG. 12</figref>. In such embodiments, the insulated regions can be defined at least in part by a space between the flat sheets <b>1014</b> and the non-planar microchannel tubing.

As another example, the sheets <b>1014</b> illustrated in <figref idrefs="DRAWINGS">FIGS. 13-14</figref> can have other insulating features, such as any of the recess shapes described above in connection with the embodiment of <figref idrefs="DRAWINGS">FIGS. 8-10</figref>. As yet another example, the microchannel tubing <b>1058</b> can be shaped to at least partially receive any of the types of insulating members described above in connection with the embodiment of <figref idrefs="DRAWINGS">FIGS. 1-4</figref>. In short, any of the features of any of the evaporator assemblies disclosed herein can be combined with any of the features from another of the evaporator assemblies so long as such features are not mutually exclusive or inconsistent with one another.

The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims. Various features and advantages of the invention are set forth in the following claims.